Up until recent years, high energy explosives and propellants such as 1,3,5-trianitraza cyclohexane ("RDX"), 1,3,5,7-tetranitraza cyclooctane ("HMX"), and trinitrotoluene ("TNT") were considered adequate for weaponry and rocketry applications. However, during the course of the last decade, the problem of unwanted detonation of these high energy explosives and propellants has become of increasing concern to the military.
Thus, the military has had to turn to other, less sensitive materials, such as 3-nitro-1,2,4-triazol-5-one (so-called "NTO"), to provide a greater margin of safety against reaction to unplanned stimuli. NTO exhibits excellent physical properties, including a desired combination of high energy when detonated and relatively low sensitivity to unplanned detonation, making it a current candidate of choice for propellant and explosives applications. Background information on NTO is provided in a technical article by K. Y. Lee and M. D. Coburn entitled "3-Nitro-1,2,4-Triazol-5-One, A Less Sensitive Explosive", Los Alamos National Laboratory (LA-10302-MS, Issued February, 1985), as well as U.S. Pat. No. 4,733,610. Various processes for producing NTO are known in the art, such as, for example, the process disclosed in the above-cited Lee and Coburn article which involves nitrating 1,2,4-triazol-5-one ("TO") by adding solid TO to a mixture containing roughly 60 volume percent of 90 percent nitric acid and 40 volume percent of water. As another illustration, European patent application 210,811, published on Feb. 4, 1987, discloses a process which involves reacting TO with 98 percent nitric acid at relatively low temperatures and with relatively long reaction times. More specifically, this European patent application discloses that TO is added to the 98 percent nitric acid during an addition time of two hours at 5.degree. C. to 10.degree. C., followed by a three hour holding period at ambient temperature, followed by quenching with water at 0.degree. C. and holding for 12 hours. Amine salts of NTO are disclosed in a technical article by K. Y. Lee and M. M. Stinecipher, entitled Synthesis and Initial Characterization of Amine Salts of 3 -Nitro-1,2,4-Triazol-5-one published in the journal Propellants, Explosives, Pyrotechnics 14, 241-244 (1989) and the Crystal Structure of Ammonium 3-Nitro-1,2,4-Triazol-5-Onate is described in the same journal in an article by L. Jiarong, C. Boren and O. Yuxiang entitled "Crystal Structure of Ammonium-3-Nitro-1,2,4-Triazol-5-one, 16, 145-146 (1991).
Hydroxylammonium nitrate (so-called "HAN"), which is the nitrate salt of hydroxylamine, is known to be an excellent insensitive oxidizer for propellants, as disclosed, for example, in U.S. Pat. No. 4,968,394 which is more specifically directed to a method for reducing excess nitric acid in aqueous hydroxylamine nitrate solutions.
The need by the military for other insensitive munitions which provide a desired combination of excellent insensitivity and enhanced impetus continues. The present invention provides one answer to that need.